Popular smoking articles, such as cigarettes, have a substantially cylindrical rod shaped structure and include a charge, roll or column of smokable material, such as shredded tobacco (e.g., in cut filler form), surrounded by a paper wrapper, thereby forming a so-called “smokable rod” or “tobacco rod.” Normally, a cigarette has a cylindrical filter element aligned in an end-to-end relationship with the tobacco rod. Preferably, a filter element comprises plasticized cellulose acetate tow circumscribed by a paper material known as “plug wrap.” Certain filter elements can incorporate polyhydric alcohols. See, for example, UK Pat. Spec. 755,475. Certain cigarettes incorporate a filter element having multiple segments, and one of those segments can comprise activated charcoal particles. See, for example, U.S. Pat. No. 5,360,023 to Blakley et al. and U.S. Pat. No. 6,537,186 to Veluz. Preferably, the filter element is attached to one end of the tobacco rod using a circumscribing wrapping material known as “tipping paper.” It also has become desirable to perforate the tipping material and plug wrap, in order to provide dilution of drawn mainstream smoke with ambient air. Descriptions of cigarettes and the various components thereof are set forth in Tobacco Production, Chemistry and Technology, Davis et al. (Eds.) (1999). A cigarette is employed by a smoker by lighting one end thereof and burning the tobacco rod. The smoker then receives mainstream smoke into his/her mouth by drawing on the opposite end (e.g., the filter end) of the cigarette.
Through the years, there have been proposed various methods for altering the composition of mainstream tobacco smoke. In PCT Application Pub. No. WO 02/37990 to Bereman, it has been suggested that metallic particles and/or carbonaceous particles can be incorporated into the smokable material of a cigarette in an attempt to reduce the amounts of certain compounds in the smoke produced by that cigarette. In U.S. Patent Application Pub. No. 2005/0066986 to Nestor et al., it has been suggested that a tobacco rod can incorporate tobacco filler combined with an aerosol-forming material, such as glycerin. U.S. Pat. No. 6,874,508 to Shafer et al. proposes a cigarette having a paper wrapped tobacco rod having a tip portion that is treated with an additive, such as potassium bicarbonate, sodium chloride or potassium phosphate.
Various tobacco substitute materials have been proposed, and substantial listings of various types of those materials can be found in U.S. Pat. No. 4,079,742 to Rainer et al. and U.S. Pat. No. 4,771,795 to White et al. Certain cigarette-type products that employ non-tobacco materials (e.g., dried vegetable leaves, such lettuce leaves) as filler that is burned to produce smoke that resembles tobacco smoke have been marketed under the trade names “Cubebs,” “Triumph,” “Jazz,” and “Bravo.” See, for example, the types of materials described in U.S. Pat. No. 4,700,727 to Torigian. Furthermore, tobacco substitute materials having the trade names “Cytrel” and “NSM” were introduced in Europe during the 1970s. Representative types of proposed synthetic tobacco substitute materials, smokable materials incorporating tobacco and other components, and cigarettes incorporating those materials, are described in British Pat. No. 1,431,045; and U.S. Pat. No. 3,738,374 to Bennett; U.S. Pat. No. 3,844,294 to Webster; U.S. Pat. No. 3,878,850 to Gibson et al.; U.S. Pat. No. 3,931,824 to Miano et al.; U.S. Pat. No. 3,943,941 to Boyd et al.; U.S. Pat. No. 4,044,777 to Boyd et al.; U.S. Pat. No. 4,233,993 to Miano et al.; U.S. Pat. No. 4,286,604 to Ehretsmann et al.; U.S. Pat. No. 4,326,544 to Hardwick et al.; U.S. Pat. No. 4,920,990 to Lawrence et al.; U.S. Pat. No. 5,046,514 to Bolt; U.S. Pat. No. 5,074,321 to Gentry et al.; U.S. Pat. No. 5,092,353 to Montoya et al.; U.S. Pat. No. 5,778,899 to Saito et al.; U.S. Pat. No. 6,397,852 to McAdam; and U.S. Pat. No. 6,408,856 to McAdam. Furthermore, various types of highly processed smokable materials incorporating tobacco and other ingredients are set forth in U.S. Pat. No. 4,823,817 to Luke; U.S. Pat. No. 4,874,000 to Tamol et al.; U.S. Pat. No. 4,977,908 to Luke; U.S. Pat. No. 5,072,744 to Luke et al.; U.S. Pat. No. 5,829,453 to White et al. and U.S. Pat. No. 6,182,670 to White et al.
Certain types of coaxial or concentric-type smoking articles have been proposed. There have been proposed cigarette-type smoking articles have included tobacco smokable materials surrounding longitudinally extending cores of other materials. UK Pat. Application 2,070,409 proposes a smoking article having a rod of smoking material having at least one filament extending over at least a major portion of the length of the rod. U.S. Pat. No. 3,614,956 to Thornton proposes a smoking article having an annular outer portion made of tobacco smoking material and a central cylindrical core of absorbent material. U.S. Pat. No. 4,219,031 to Rainer et al. proposes a smoking article having a central core of carbonized fibers circumscribed by tobacco. U.S. Pat. No. 6,823,873 to Nichols et al. proposes a cigarette including an ignition element surrounded by tobacco, which is in turn surrounded by a composite outer wrapper. One type of cigarette-type smoking article has included a rod of tobacco smokable material surrounded a longitudinally extending annulus of some other material. For example, U.S. Pat. No. 5,105,838 to White et al. proposes a rod of smokable material, normally circumscribed by a layer of wrapping material, which is in turn circumscribed by an insulating material (e.g., glass filaments or fibers). PCT Application Pub. No. WO 98/16125 to Snaidr et al. proposes a smoking device constructed from a very thin cigarette designed to fit into a tubular ceramic cartridge.
Numerous references have proposed various smoking articles of a type that generate flavored vapor, visible aerosol, or a mixture of flavored vapor and visible aerosol. Some of those proposed types of smoking articles include tubular sections or longitudinally extending air passageways. See, for example, those types of smoking articles described in U.S. Pat. No. 3,258,015 to Ellis et al.; U.S. Pat. No. 3,356,094 to Ellis et al.; U.S. Pat. No. 3,516,417 to Moses; U.S. Pat. No. 4,347,855 to Lanzellotti et al.; U.S. Pat. No. 4,340,072 to Bolt et al.; U.S. Pat. No. 4,391,285 to Burnett et al.; U.S. Pat. No. 4,917,121 to Riehl et al.; U.S. Pat. No. 4,924,886 to Litzinger; and U.S. Pat. No. 5,060,676 to Hearn et al. Many of those types of smoking articles have employed a combustible fuel source that is burned to provide an aerosol and/or to heat an aerosol-forming material. See, for example, the background art cited in U.S. Pat. No. 4,714,082 to Banerjee et al. and U.S. Pat. No. 4,771,795 to White et al.; which are incorporated herein by reference in their entireties. See, also, for example, those types of smoking articles described in U.S. Pat. No. 4,756,318 to Clearman et al.; U.S. Pat. No. 4,714,082 to Banerjee et al.; U.S. Pat. No. 4,771,795 to White et al.; U.S. Pat. No. 4,793,365 to Sensabaugh et al.; U.S. Pat. No. 4,917,128 to Clearman et al.; U.S. Pat. No. 4,961,438 to Korte; U.S. Pat. No. 4,966,171 to Serrano et al.; U.S. Pat. No. 4,969,476 to Bale et al.; U.S. Pat. No. 4,991,606 to Serrano et al.; U.S. Pat. No. 5,020,548 to Farrier et al.; U.S. Pat. No. 5,033,483 to Clearman et al.; U.S. Pat. No. 5,040,551 to Schlatter et al.; U.S. Pat. No. 5,050,621 to Creighton et al.; U.S. Pat. No. 5,065,776 to Lawson; U.S. Pat. No. 5,076,296 to Nystrom et al.; U.S. Pat. No. 5,076,297 to Farrier et al.; U.S. Pat. No. 5,099,861 to Clearman et al.; U.S. Pat. No. 5,105,835 to Drewett et al.; U.S. Pat. No. 5,105,837 to Barnes et al.; U.S. Pat. No. 5,115,820 to Hauser et al.; U.S. Pat. No. 5,148,821 to Best et al.; U.S. Pat. No. 5,159,940 to Hayward et al.; U.S. Pat. No. 5,178,167 to Riggs et al.; U.S. Pat. No. 5,183,062 to Clearman et al.; U.S. Pat. No. 5,211,684 to Shannon et al.; U.S. Pat. No. 5,240,014 to Deevi et al.; U.S. Pat. No. 5,240,016 to Nichols et al.; U.S. Pat. No. 5,345,955 to Clearman et al.; U.S. Pat. No. 5,551,451 to Riggs et al.; U.S. Pat. No. 5,595,577 to Bensalem et al.; U.S. Pat. No. 5,819,751 to Barnes et al.; U.S. Pat. No. 6,089,857 to Matsuura et al.; U.S. Pat. No. 6,095,152 to Beven et al; U.S. Pat. No. 6,578,584 Beven; and U.S. Pat. No. 6,730,832 to Dominguez. Furthermore, certain types of cigarettes that employ carbonaceous fuel elements have been commercially marketed under the brand names “Premier” and “Eclipse” by R. J. Reynolds Tobacco Company. See, for example, those types of cigarettes described in Chemical and Biological Studies on New Cigarette Prototypes that Heat Instead of Burn Tobacco, R. J. Reynolds Tobacco Company Monograph (1988) and Inhalation Toxicology, 12:5, p. 1-58 (2000).
Yet other types of smoking articles, such as those types of smoking articles that generate flavored vapors by subjecting tobacco or processed tobaccos to heat produced from chemical or electrical heat sources are described in U.S. Pat. No. 4,848,374 to Chard et al.; U.S. Pat. No. 4,947,874 to Brooks et al.; U.S. Pat. No. 5,146,934 to Deevi et al.; U.S. Pat. No. 5,224,498 to Deevi; U.S. Pat. No. 5,285,798 to Banerjee et al.; U.S. Pat. No. 5,357,984 to Farrier et al.; U.S. Pat. No. 5,593,792 to Farrier et al.; U.S. Pat. No. 5,369,723 to Counts; U.S. Pat. No. 5,865,185 to Collins et al.; U.S. Pat. No. 5,878,752 to Adams et al.; U.S. Pat. No. 5,880,439 to Deevi et al.; U.S. Pat. No. 5,915,387 to Baggett et al.; U.S. Pat. No. 5,934,289 to Watkins et al.; and U.S. Pat. No. 6,164,287 to White; and U.S. Patent Application Pub. No. 2005/0016549 to Banerjee et al. One type of smoking article that has employed electrical energy to produce heat has been commercially marketed by Philip Morris Inc. under the brand name “Accord.”
Smoking articles that employ tobacco substitute materials and smoking articles that employ sources of heat other than tobacco cut filler to produce tobacco-flavored vapors or tobacco-flavored visible aerosols have not received widespread commercial success. It would be highly desirable to provide a smoking article, such as a cigarette, that includes the ability to provide to a smoker many of the benefits and advantages of conventional cigarette smoking without delivering considerable quantities of incomplete combustion and pyrolysis products.